1. Field of the Invention
This invention relates generally to micro-electro-mechanical system (MEMS) mirrors, and more particularly, to a MEMS resonant scanning mirror driver circuit.
2. Description of the Prior Art
Movement of a resonant MEMS mirror is accomplished using a control loop that includes a sinusoidal driver circuit. This driver circuit must have low harmonic distortion characteristics in order to precisely and accurately control movement of the MEMS mirror. Such driver circuits generally require use of either a precision analog oscillator or a fast and therefore expensive digital-to-analog converter (DAC) devices and accompanied sine wave logic to control the amplitude of the drive signal to a MEMS resonant scanning mirror.
In view of the foregoing, it would be desirable and advantageous in the MEMS mirror art to provide a resonant scanning mirror driver circuit that allows use of an inexpensive means of generating the sine wave and an inexpensive DAC with a relatively slow sample rate commensurate with a microprocessor based control algorithm.
The present invention is directed to a MEMS resonant scanning mirror driver circuit. The driver circuit has separate amplitude and waveshape inputs which allows a relatively slow and therefore inexpensive DAC to be used to control the amplitude of the drive signal for the MEMS device.
According to one embodiment, a resonant scanning mirror driver circuit is provided that has an analog input to set the amplitude of a sinusoidal drive voltage and further has a PWM digital input that generates the sinusoidal waveform.